Changing Populations A. 1.

Name
Date
Class
Chapter 21
Lesson Outline
LESSON 2
Changing Populations
A. How Populations Change
1. A population’s
is the number of offspring produced
over a given time period. The
individuals that die over the same time period.
is the number of
2. When a population is in ideal conditions with unlimited resources, it grows in a
pattern called
.
3. During exponential growth, as a population gets larger, it grows at a(n)
rate.
4. Food shortages, natural disasters, disease, and
can
reduce population size.
5. A(n)
is a species that has died out and has no living
individuals.
6. Extinctions can be caused by predation, natural disasters, or damage to
the
7. A(n)
.
is a species whose population is at risk of
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
extinction.
8. A(n)
is a species that is at risk but is not yet
endangered.
9. Populations change when organisms
from place to
place.
a. Animals move to less
b. Wind and
places.
can spread plant seeds far from their
parent plants.
10.
is the instinctive seasonal movement of a population
of organisms from one place to another. Many animals migrate to where
is more available.
B. Human Population Changes
1. Human population size is affected by the same three factors that determine the
sizes of all populations—birthrate, death rate, and
.
2. Unlike other species, humans have developed ways to increase the
of their environment.
Populations and Communities
27
Name
Date
Class
C21L2
Lesson Outline continued
3. Human population growth can have negative effects on
other
.
4. Better access to food and other
, such as fossil fuels,
cloth, and metals, has led to human birthrates being higher than death rates.
5. Improvements in water treatment and medical care have helped reduce
human
.
6. Human populations in some parts of the world are decreasing due to
, drought, and natural disasters.
7. Humans commonly move from place to place, affecting the local
size.
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
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Populations and Communities